Mercury is absolutely toxic to the adrenals. So it is entirely possible that the mercury is causing adrenal symptoms.
You are very lucky. It cost me $4500 to get all the mercury out of my mouth. If you have the money I would say get them out ASAP.
Instead of charcoal, I took IP6 the day of removal. It worked beautifully. I took quite a bit before, then I rinsed my mouth out with some IP 6 and water immediately after and spit it out. Then I took some more. I had zero symptoms from removal
If you're going to use the activated charcoal, then I would recommend that you also rinse out your mouth immediately afterwords with some type of calcium-based clay and water. This will bind to any free-floating Mercury left in your mouth and remove it.
remember to use plenty of vitamin C and potassium citrate to support and cleanse your kidneys and adrenals